A Search for Wide Companions to the Extrasolar Planetary System HR 8799

Abstract

The extrasolar planetary system around HR 8799 is the first multiplanet system ever imaged. It is also, by a wide margin, the highest mass system with >27 Jupiters of planetary mass past 25 AU. This is a remarkable system with no analogue with any other known planetary system. In the first part of this paper we investigate the nature of two faint objects imaged near the system. These objects are considerably fainter (H=20.4, and 21.6 mag) and more distant (projected separations of 612, and 534 AU) than the three known planetary companions b, c, and d (68-24 AU). It is possible that these two objects could be lower mass planets (of mass ~5 and ~3 Jupiters) that have been scattered to wider orbits. We make the first direct comparison of newly reduced archival Gemini adaptive optics images to archival HST/NICMOS images. With nearly a decade between these epochs we can accurately assess the proper motion nature of each candidate companion. We find that both objects are unbound to HR 8799 and are background. We estimate that HR 8799 has no companions of H<22 from ~5-15 arcsec. Any scattered giant planets in the HR 8799 system are >600 AU or less than 3 Jupiters in mass. In the second part of this paper we carry out a search for wider common proper motion objects. While we identify no bound companions to HR 8799, our search yields 16 objects within 1 degree in the NOMAD catalog and POSS DSS images with similar (+/-20 mas/yr) proper motions to HR 8799, three of which warrant follow-up observations.

22 pages, 8 figures, submitted to the Astrophysical Journal

References in corpus (12)

• Direct Imaging of Multiple Planets Orbiting the Star HR 8799
• Empirical Color Transformations Between SDSS Photometry and Other Photometric Systems
• The Gemini Deep Planet Survey -- GDPS
• The Debris Disk Around HR 8799
• The Formation Mechanism of Gas Giants on Wide Orbits
• HST/NICMOS detection of HR 8799 b in 1998
• The Wide Brown Dwarf Binary Oph 1622-2405 and Discovery of A Wide, Low Mass Binary in Ophiuchus (Oph 1623-2402): A New Class of Young Evaporating Wide Binaries?
• Constraints on Extrasolar Planet Populations from VLT NACO/SDI and MMT SDI and Direct Adaptive Optics Imaging Surveys: Giant Planets are Rare at Large Separations
• Long period planets from dynamical relaxation
• Is the HR 8799 extrasolar system destined for planetary scattering?
• The First Direct Distance and Luminosity Determination for a Self-Luminous Giant Exoplanet: The Trigonometric Parallax to 2MASS1207334-393254Ab
• H band Image of a Planetary Companion around HR 8799 in 2002

Cited by in corpus (9)

• The VAST Survey - III. The multiplicity of A-type stars within 75 pc
• Near-Infrared Spectroscopy of the Extrasolar Planet HR 8799 b
• The Gemini NICI Planet-Finding Campaign: The Frequency of Planets around Young Moving Group Stars
• Constraining the initial entropy of directly-detected exoplanets
• A Uniform Analysis of 118 Stars with High-Contrast Imaging: Long Period Extrasolar Giant Planets are Rare around Sun-like Stars
• Thermal Infrared MMTAO Observations of the HR 8799 Planetary System
• Secular Orbital Dynamics of Hierarchical Two Planet Systems
• Remnant gas in evolved circumstellar disks: Herschel PACS observations of 10-100 Myr old disk systems
• Deep orbital search for additional planets in the HR 8799 system